Had a bit more luck this time.
My missing systemd service was from a bad misconfiguration where I tried to insert my own ssh-agent.service in ~/.config/systemd
and so systemd just completely deletes any mention or idea of that service if there’s any error loading it. Not even close to optimal fault-mode behavior on systemd’s behalf, but let’s move on. So that’s back.
And this was my actual problem at the root:
In my perfect world, it should definitely be “fixed” upstream to match the config I use for all of my other distros. I wonder why it is missing that, if it has historical reasons or if it’s just a simple omission.
Thanks for the tips on that, BluishHumility!